Is salinity tolerance the key to success for the invasive water bug Trichocorixa verticalis?

Abstract

Trichocorixa verticalis is a North American water bug (Heteroptera: Corixidae) that occurs in brackish and saline aquatic systems. Recently, it has been found invading three continents including Europe. Its invasive success has been attributed to the capacity of tolerating hypersalinity. We compared both the realized and standardized salinity niche of invasive T. verticalis and native Corixidae to verify if T. verticalis may fill in an unoccupied niche. We first established the field distribution of T. verticalis and native Corixidae along a salinity gradient. Second, we experimentally tested the salinity tolerance of T. verticalis and three common native Corixidae species. Of the seven Corixidae species found in the field study, three were positively related to the salinity gradient: S. selecta, S. stagnalis, and T. verticalis. T. verticalis showed the highest salinity optimum, however, after correcting for environmental background variation, salinity optima differed little among the three halophilic species. In the salinity tolerance experiment, S. selecta outperformed T. verticalis, which performed as well as S. stagnalis. Based on our experimental results, we cannot support the hypothesis that T. verticalis' invasion is mediated by a high salinity tolerance that allows this species to colonize habitats unoccupied by native Corixidae. Although these findings contrast with the field patterns in which T. verticalis showed the highest niche optimum and tolerance, these patterns may have been partly due to other environmental factors, particularly anthropogenic disturbance. Our comparative results are for adults only, and it remains possible that relative salinity tolerance patterns for juveniles differ from that for adults, which may add to the observed field pattern.

Sensitivity of native and non-native mollusc species to changing river water temperature and salinity

“…The difference between native and non-native species can be explained by the origin of species, as previous studies found significantly higher temperature tolerances for (sub)tropical than for temperate species (De Vries et al 2008). Salinity tolerances of native and non-native species were not significantly different, which agrees with other recent studies on salinity tolerance of native and non-native macroinvertebrates (Piscart et al 2011;Van de Meutter et al 2010). However, our results also show that some non-native species can tolerate considerably higher salinities than native species.…”

Parasitism by water mites in native and exotic Corixidae: Are mites limiting the invasion of the water boatman Trichocorixa verticalis (Fieber, 1851)?

“…v. verticalis is a highly successful invader in coastal wetlands of higher salinities in the southern Iberian Peninsula (Rodríguez-Pérez et al 2009;Van De Meutter et al 2010b;Guareschi et al 2013). Although information remains limited, its ability to outcompete native corixids at high salinities seems to be related to its high fecundity and a capacity to complete several generations a year.…”

“…In contrast, native corixids dominate in seasonal ponds and marshes of lower salinity within the same general area (Rodríguez-Pérez et al 2009; Van de Meutter et al 2010a). This strong pattern in relation to salinity remains unexplained, especially as experiments with adult corixids have shown that T. v. verticalis adults perform well at low salinities and are not more resistant to high salinities than some native corixids ( Van de Meutter et al 2010b;Coccia et al 2013). Indeed, the native Sigara selecta (Fieber, 1848) is more halotolerant than T. v. verticalis ( Van de Meutter et al 2010b).…”

Water beetle tolerance to salinity and anionic composition and its relationship to habitat occupancy

“…In addition, under low salinity conditions, some species show osmoregulatory ability to varied solute composition but the capacity for such flexibility is reduced in species that inhabit waters with higher salinity (Herbst, 2001). Many studies focus separately on the effects of salinity (e.g., Kefford et al, 2006;Van de Meutter et al, 2010) or ionic composition (e.g., Zalizniak et al, 2009) on species, but the interaction between these factors has been less thoroughly explored (but see Sheplay and Bradley, 1982;Carbonell et al, 2012).…”